I was driving today and my phone was in its holder. At the time, I was using it for GPS and Pandora, and it was plugged in using my car charger. At one point, the notification LED began to flash in what looked like a regular pattern (but since I was driving, I can't be 100% sure), alternating between green and amber. I've never seen this before, and I had no notifications. What does it mean?

Although there's no official documentation, the discussion forums seem to back this up. Unfortunately, I have no desire to test this out myself...until someone can find concrete reasons why this might not be the reason, I'm going to accept this answer.
–
Thomas OwensDec 7 '10 at 15:32